[jira] [Created] (DRILL-57) Add a logical operator that returns a constant result, similar to VALUES operator in SQL

["Julian Hyde (JIRA)" <ji...@apache.org>]

Julian Hyde created DRILL-57:
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             Summary: Add a logical operator that returns a constant result, similar to VALUES operator in SQL
                 Key: DRILL-57
                 URL: https://issues.apache.org/jira/browse/DRILL-57
             Project: Apache Drill
          Issue Type: Bug
            Reporter: Julian Hyde


Add a logical operator that returns a constant result. This is necessary to be able to create values out of thin air, if you don't know what tables exist.

This operator is analogous to the VALUES operator in SQL. For example,

  VALUES (1, 'a'), (2, 'b'), (3, 'c')

returns 2 rows with 3 columns and

  VALUES (1, 'a'), (2, 'b'), (3, 'c') AS t(c1, c2)

allows you to name those columns "c1" and "c2". VALUES is useful for evaluating expressions that don't belong in a table, for example

  VALUES 10 + 3

(Some databases would express this "SELECT 10 + 3". Same idea, and same underlying relational operator.)

The JSON for this new operator might look like this:

	    {
	      op: "constant",
              content: { [
                {c1: 1, c2: "a"},
                {c1: 2, c3: ["x", "y", "z"]}
              ] }
	    }

This operator is necessary in order to implement the SQL VALUES clause.

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